What does "!" mean in pseudo-code? I know "!" stands for factorial but I can't translate it

Question

What does ! mean in pseudo-code? I know ! stands for factorial but I can't translate it .

ex:

get operation

if (operation!= ’B’ OR operation != ’D’ OR operation!= ’W’) then
    print "Invalid Operation"

What does it mean? Please help my mid-term is in hours :S

Thanks in advance for your help :)

Answer 1

!= means not equal and ! generally means not or negation.

Answer 2

It means "not". So your example code

if (operation!= ’B’ OR operation != ’D’ OR operation!= ’W’)

can be read as

"If operation does not equal 'B' or operation does not equal 'D' or operation does not equal 'W'"

Answer 3

In general,

!   means   not
|| means logical or
&& means logical and

Example:

!false == true  ( == means equality )